This invention relates to a socket for dual in line package integrated circuits, and more particularly relates to such a socket which requires larger forces for withdrawal of such package than for insertion thereof.
Typical electrical connectors use fork contacts supported in a housing, and each contact has opposed fork portions usually bent toward each other for wiping opposite sides or edges of an electrical lead during insertion thereof so as to form an electrical connection therebetween. During ingress of the lead into engagement with a single or double fork contact, large axial friction and mechanical forces are required to urge the lead past the forward-most portions of such contacts due to their geometry in order to achieve sufficient lateral motion of the forks for full insertion of the leads into the connector. Such axial forces are subsantially higher on ingress than on egress because in the former the contact geometry must be changed to permit the lead to pass, whereas in the latter there is no geometry change but rather merely a spring-like friction force exerted by the contact on the lead.
Since the leads of conventional integrated circuit packages are usually quite frail, it is desirable to avoid direct soldering or other type of attachment thereof to external circuits; thus, integrated circuit sockets are used which have contact leads for direct engagement to such external circuits and contact connecting portions for respectively connecting leads of such package. Integrated circuit sockets are used primarily to effect connections between the leads of an integrated circuit package and external circuitry, for example, on a printed circuit board by soldering the contacts of the socket to the board. One area of concern with electrical connectors and particularly with integrated circuit sockets for dual in line packages is that the socket must exert adequate holding power on the package leads to preclude inadvertent separation and that the force required for insertion of the package leads into the socket be sufficiently small to avoid damage to the frail leads. To effect these functions many prior art integrated circuit sockets require a third member which is actuated to lock the socket contact into retaining engagement with respective inserted leads, for example, by changing the geometry of such contact. In order to achieve desired holding power or retention characteristics in prior art sockets without such third member, the contacts must require a high insertion force on the order of one pound per lead, which are frail and subject to buckle or other damage when inserted with such force.